Liquid-level indicator



March 27, 1928.

Filed March 11, 1925 INVENTOR:

Patented Mar. 27, 1928.

THOMAS Ml Erma; 0's rHILAnELrHiA, PENNSYLVANIA;

LIQUID LEVEL INDICATOR." 1

, Application fildMarch 11, was; seriai No. 14,61'3

My invention relates to a new and useful liquid level measuring device,gaug'e or indicator, whereby the level of the liquid in a vessel'may beindicated on a 'scalelocated remotely from the liquid to' be. measured,

and whereby an accurate reading may be characters ind cate like partsobtained on said'scale regardless ofthe pressure in "said vessel andregardless ofvariationsof temperature of the l quid or of the,

' my invention,

various parts ofthe instrument 1 invention rams particularly-to a novelliquidlevel indicator,"which is capable of general application, but isespecially adapted for utilization-in connection with the instrumentboard of an automobile to;

indicate the height of the gasoline .level, and hence the quantity ofgasoline, in, the

gasoline tanlg'and it relates more particular- 1y to aliquid levelindieatoiiwhich is espe "cially adaptedfor use-in connection with-thepressure system of gasohne storage and supply, commonly used on bettergrade of automobiles although my invention is equal- 1y applicable togravity or vac uuin systems of gasoline supply on automobiles.

\Vith theabove ends in view myinven'tioii 3 consists of a novelconstruction of an auto matic liquid level indicating device, operatedsolely bytlie pressure caused on a pre ssure sensitive diaphragm on thebottom of the liquid, bythe weight of the liquidabove the diaphragm, andwherein the level indicated,

will be independent of the pressure in the I tank or 'on the surface ofthe liquid, and; "wherein such tank pressure is compensated for, and itseffect eliminated, by means of a second pressure sensitive diaphragm atthe top of the tank said two 'diaphrag'ms' beingf 'diaphragins 7 and8'secured-to two heads 9 and 10 respectively, in' a fluidtig'ht manneras shown particularly in-Eigure 1, the lower connected hydraulically ftothe two opposed 'sidesof a gauge or, indicator.

My invention further consists of "a novel automaticliquidlevellindicating device having'a minimum number of movingipartsand which will register accurately regardless of moreover is applicableto all islo cated on the chassis.

' 'For he purpose of in practice to give satisfatoryj and reliableresults, althouglifit islto beunderstood uiati the vari us instriiiientaliti'e's' of which my 'ured, on whioh instrumentbjoa'rd aremounted the gauge glasses and 5 parallel toeach other," and the scale'Gpositioned between'the 'llustratiiig l my! in: veiition, 'I have shownin the accompanying if drawings forms thereof which are alt-presentpreferred byimdsinc'e theyfhave been foun invention consists can'be,variously arranged, and organized and that my nvention is not 1 limited.to the precise arrangement and or ganization ofthese instrumentalitiesas herein' shown and describedf In tlie'drawings *in which likereference vFigure represents a front elevation partly in section, of afluid gauge embodying F igiire 2 represents a front elevation, on areduced scale showing an application of.

" my invention.

Figure 3 represents a section on line l of Figure 1. ,j I

'Figure 4 represents a section on line/1+4 of Figure 1 i t t i Referringto the drawings 1- designates a] tank'or other vessel containing aliquid 2f" -wh1cli is tobe measured bj fin'dicat ng. ;the J a levelthereof. the specific embochinentof l my invention shown inj thedrawings, the

tank 1 represents agasoline orfuel tank ofa' motor c i iand' is of thepressure ty e;

where n the gasoline orvothe'r fuel liquid is a forced from the min; tothe engineby, means ofgas pres'su e'exerted on the," surface of cable'however to thejgravity or vacuum automobile usually located remotelyfrom i the tank 1 containing the liquid to be meastwo glasses. 1 4 t Mynovel indicator'consists chiefly of two -the,liq'uid. My invenuon is'equally'applidiaphragm [7 being-secured between the annular surface 11of the lower head 9, and

ervious' to the liquitito be'measurw, and" thjupp'er' head '10, and; theedfrespniidiiig which is at the same time not deteriorated,

' or in any way affected by such liquid.

In the particular embodiment of" my. invention shown in the drawings andto be described in detail hereinafter, the liquid 2 to be measured isgasoline or some other similar mixture of liquid, hydrocarbons ofmineral origin, and the diaphragms 7 and 8 are therefore preferably madeof celluloid of a suitable thickness, which. material has been found inpractice to be durable, strong,

and not effected by the solvent power of gasoline. V V

The spacing rod 20, extends betweenthe centers of the two diaphragms'7and 8, and is secured fixedly to said diaphragms by means of the twonuts 21 and 22, on the bottom'and 23 and 24 011 thetop; the rod 20passing through a small aperture in the center of each of saiddiaphragms. In order to permit the adjustment of the length of therod20, so as to permit the adjustment on the instrument, the rod isbroken at 25,

' with the two ends 26 and 27 threaded in opposite directions, and has acorresponding threaded sleeve 28 connecting the two ends. Through asuitablepipe 29, preferably a thin copper tubing, ajfluid-tightconnection v and liquid communication is established be tween the lowerend of the gauge glass i and the chamber 30 of the lower head9, whichchamber in turn is in direct communication with the lower face of thediaphragm 7, through'the series'of apertures 31 pro- 'vided in the upperwall 32 of the head 9.

The upper end of the gauge glass t communicates with the upper end ofthe second gauge glass 5, through a suitable pipecon nection or otherfluid tight passageway 33, thereby forming an inverted U tube having theglass or other transparent limbs i and5. The lower end-of the gaugeglass 5 in turn connects with the chamber 34: of the upper headlOthrough a suitable pipe 35. i

As will be-seen from Figure 2 the measuring unit 36 is inserted into thetank 1 through a suitable opening 37 in the top of tank, into whichopening it is secured by means of the threaded portion 38 on the outerhead 10.

"The measuring unit 36 thus inserted into the tank to the bottomthereof, will be di rectly immersed into the gasoline or other a liquidcontained in the tank. Through suitable 0 )enin s 39 and 40 around thebottom andtop of said spacing cylinder 13 a direct communication isestablished at all times between the liquid in the tank, and the diaphragms 7 and 8. Thus by filling the pres sure chambers 30 and. 34},the connecting tubes 29 and 35 and the indicator or gauge glasses i and5 with a suitable liquid indicator medium, preferably a non-volatilevegetable oil, up to the level indicated approximately by the zero markon the scale 6, any

nee-1,200

difference in pressure on the two diaphragms 7 and 8', will cause thediaphragm bearing the greater pressure deflect towards the correspondingpressure chambers, and to force the indicator-liquid; out'ofsaidchamber; thereby raising the level of the liquid mediumv in thecorresponding gauge Thus on filling the tank 1 with liquid such asgasoline the pressure on the lower diaphragm 7 will be greater than thepressure. on the upper diaphragm 8, by an amount.

equal tothe weight of the gasoline on said,

' lower diaphragm,and the diaphragms being unbalance'chwill raise thelevel of the liquid ured in any units. desired such as quart-s,

gallons, or the like.

In. order to completely equalize the normal or zero? pressure 'on thetwo diaphragms 7 and 8, in the normal positions thereof, that is whenthe lower diaphragm is not submerged in a liquid, it is necessary thatthe exposed areas of the two diaphragms shall be exactly alike. In orderto eliminate any inaccuracies in the readings on' the gauge glasses atand 5, which might be caused by variations in the temperature oftheliquid, or parts of the instrument, and the resulting unequalexpansion of'the liquid indicator medium contained therein, these twotubes 1 must be substantially equal in length, and

must be unexposed to the same variations of temperature as well aspressure; Since the tube 29 extends to the bottom of the measuring unit36,- namely to the lower head '9, and

the tube 35 extends only to the top of said I measuring'unit 36, namelyto the upper head 10, such tubes are of unequal length, and I,therefore, join to the lower end of the shorter tube 35, a tube 41which, is also filled with the liquid indicator medium and communicateswith the tubel35, extends into the tank 1 and is substantially of alength to make the total or eifectivelengths of the two tubes 29 and 35equal.

It will be apparent tion that by means of my novel measuring unit 36 andthe cooperating'gauge glasses 4 v, and 5, it is possible tomeasure theliquid in j any tank, regardless of whether the pressure in such tank isatmospheric, above atmospheric, or below atmospheric. This wideapplicability of my instrument is due tothe fact, that regardless ofwhatever pressure may be in the tank or on the surface of the liquidcontained therein, the two diaphragms from the above descrip- 7 and 8are affected equally by such pressure, since both diaphragms are exposedto it alike, and therefore-the pressure within the tank or on thesurface of the liquid will not be registered by the indicator liquid inthe gauge glasses 4 and 5. It is only the difference in the pressures onthe two diaphragms 7 and 8, caused by the weight of the liquid 2,containing in the tank 1, bearing on the lower diaphragm 7, which willbe recorded or indicated in the gauge glasses 4: and 5.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent, is

1. In a device of the character stated, a lower pressure sensitivediaphragm, an upper pressure sensitive diaphragm, means for retainingsaid diaphragms in constant relation to each other, and liquid conduitscom municating with said diaphragms respectively for containing liquidcolumns adapted to be supported by said diaphragms for indicating thedifference of pressures on said two diaphragms.

2. In a device of the character stated, a housing, a lower and an upperchamber at the respective ends of said housing, pressure sensitivediaphragms closing said chambers, an indicating device, passagewaysconnecting said indicating device with said chambers, and a liquidindicating medium filling said chambers and said passageways.

3. In a device of the character stated, a lower and an upper head,chambers in said heads, a lower and an upper diaphragm closing therespective chambers in said heads, a housing common to said heads forretaining the same in constant spaced relation to each other. I

4. In a device of the character stated,fla lower and an upper headlocated at a fixed distance from each other, pressure chambers in saidheads, pressure sensitive diaphragms closing said chambers, a continuouspassageway connecting said two chambers having twosubstantially'parallel and adjacent upright portions of a transparentmaterial, a

scale in proximity to said transparent portions, and a liquid indicatingmedium filling -way connecting said two chambers having twosubstantially parallel and adjacent upright portions of a transparentmaterial, a

scale in proximity to said transparent portions, and a liquid indicatingmedium filling said chambers and said passageways to substantially thelevel of the center of said scale, a means common to said two diaphragmsfor retaining the same in constant relation to each other.

6. In a device of the character stated, a

lower and an upper head located at a fixed distance from each other,pressure chambers 1n said heads, pressure sensitive diaphragms closingsaid chambers, a continuous passageway connecting said .two chambershaving two substantially parallel and adjacent upright portions of atransparent material, a scale in proximity to said transparent portions,and a liquid indicating medium filling said chambers and saidpassageways to substantially the level of the center of said scale, ameans common to said two 'diaphragms for retaining the same in constantrelation to each other, a compensating tube communicating with the upperpressure chamber and extending into the liquid to be measured forcompensating for temperature variations of the liquid- 7. In a device ofthe'character stated, a liquid holding tank, a spacing member or housingpassing through the top wall of said tank and extending in proximity tothe bottom wall thereof, a lower and an upper chamber at the respectiveends of said housing, pressure sensitive diaphragms closingsaid'chambers, means remotely located with respect to said diaphragmsand hydraulically connected with the same, forindicating the differenceof pressures on said two, diaphragms.

THOMAS M. EYN ON.

